Preparation and application of sustainable nanofluid lubricant from waste soybean oil and waste serpentine for green intermittent machining process

A great amount of waste cooking oil (WCO) and waste serpentine arise in daily life or industrial production. Serpentine is a type of hydrated magnesiumsilicate often employed as flux material for steel industry. Recycling of WCO and waste serpentine is of great significance to the solution of environmental issues and the promotion of economy. On the other hand, machining process has great impacts on global economy. Large amounts of mineral oil-based lubricant are consumed by the machining process, causing many health and environmental problems. Thus, this work studied preparation and application of sustainable nanofluid lubricant from waste soybean oil (WSO) and waste serpentine for green intermittent machining process. WSO hydrolysis and free fatty acids esterification were used to acquire modified WSO (MWSO). Epoxidized soybean oil (ESO) and MWSO constituted the base oil. The base oil was adjusted by changing the volume ratio VR of ESO to MWSO. Serpentine nanoparticles were obtained by mechanically reducing the size of waste serpentine particles. The volume fraction Vp of nanoparticles in the lubricant was set to have different values. Bioinspired hexagonal recessed microstructure was fabricated on tool surface for performance enhancement of the lubricant. The results revealed that the parameter combination of VR = 50% and Vp = 2.1% resulted in the optimum friction performance and cutting performance at relatively low cost. This work offered a new solution to the sustainable nanofluid lubricant used in green intermittent machining process. Moreover, the proposed solution provided new economic opportunity.